Multiple laser safety system

ABSTRACT

A method of operating a safety system for an industrial press having a moveable section and a stationary section, the safety system providing a plurality of continuous planar laser beams having a generally constant lateral width, each laser beam being spaced at varying distances from the moveable section, the method including moving the moveable section towards the stationary section at a relatively high speed; starting deceleration of the moveable section when one said laser beam reaches a speed control point located immediately adjacent the stationary section, moving the moveable section at a final crawl speed when a second said laser beam reaches the speed control point, the moveable section continuing to move at said final crawl speed towards said stationary section.

The present invention is generally directed to safety systems used inindustrial applications, and in particular to safety systems for use onindustrial presses such as a press brake or guillotine. Although thepresent invention will now be described with respect to press brakes, itis to be appreciated that other applications of the present inventionare also envisaged.

The Applicant has developed an industrial press safety system utilisinga laser emitting a single continuous planar laser beam having agenerally constant lateral width and a light receiver for the laser.Both the laser and the light receiver are mounted on the moveablesection of the industrial press. In the case of a press brake, the laserand light receivers are mounted on the moveable tool, and the tool (andlaser and light receiver mounted thereon) moves relative to a stationaryanvil section. This safety system is described in International PatentApplication PCT/AU00/00420, details of which are incorporated herein byreference.

The safety system acts to prevent operators of the press brake fromaccidentally trapping their hands or other objects between the tool andanvil while operating the press brake. This is achieved by locating theplanar laser beam between the tool and the anvil. Any breaking of thelaser beam path by an object is detected by the safety system which actsto immediately stop further movement of the tool. The safety systemoperates in this manner during the movement of a tool towards the anviluntil the tool is in close proximity to the anvil. At that time, thesafety system must slow the speed of movement of the tool and shut offthe laser to allow the tool to complete its bending operation on a plateor other object located over the anvil. A speed control point is presetby the operator a small distance above the anvil and generally coincideswith the top surface of the workpiece on the anvil.

The brake press using a safety system as described above can typicallyoperate using the following operational cycle:

a) If no obstruction is detected during the downward travel of the tool,then the tool moves at high speed (typically about 150 mm/s) towards theanvil. When the laser beam, which is located below the tool, passes thespeed control point, the tool slows to a crawl speed (typically about 10mm/s). The slowing of the tool speed ensures that there is stillsufficient time to withdraw a finger or other object from under the toolat the final approach of the tool to the anvil.

b) If an obstruction is detected, the tool will be stopped and reverseda few millimetres so that the tool will not touch the obstruction. Themovement of the tool can be continued by the operator using a footswitch. If a further obstruction is detected, then the tool is stoppedbut not reversed. This enables thicker workpieces to be processed as theoperator will allow completion of the cycle by actuating the foot switchto thereby move the tool at crawl speed.

The above described operating cycle is the normal mode of operation.Other operational cycles can alternatively be used, for example, a “traymode” for the production of trays or boxes. This tray mode is describedin the above noted International Patent Application and will not bedescribed in detail here.

The aim of our device is to protect the operator of the press brake atall times. It is considered that the operator is protected if the pressis slowed to 10 mm/sec (with tolerance) or if a physical barrier or alight sensing device including our type of system is active. Thereforeto provide this continuous protection we slow the press brake to 10mm/sec before we switch off, or desensitize (mute is a word that issometimes commonly used) our laser beam or beams.

The spacing between the laser beam relative to a leading edge of thetool is generally the distance at which the tool must step at highspeed. The spacing of the laser beam can for example be set at about 9.0mm, and the tool controlled to be able to stop with a distance less thanthe above noted spacing, for example about 8.5 mm. It would however beadvantageous to be able to operate the brake press at higher speeds toreduce production times. To this end, it is envisaged that the highspeed of the travel of the tool be increased to about 200 to 220 mm/s ascompared with 150 mm/s of current press brakes. This however makes itmore difficult to use the above described safety system because thelaser beam would need to be located further away from the tool toprovide for an acceptable stopping distance for the tool. This howeverresults in the crawl speed of the tool being activated earlier when thelaser reaches the speed control point thereby lengthening the time whenthe tool is moving at the crawl speed. This at least reduces the benefitachieved in faster production lines due to the higher tool travel speed.

It is therefore an object of the present invention to provide animproved safety system for an industrial press that allows the press tooperate at higher speeds thereby facilitating shorter production times.

It is another object of the present invention to provide an improvedmeans of operating a safety system for an industrial press to therebyallow for the press to operate at higher speeds. With this in mind,according to one aspect of the present invention, there is provided asafety system for an industrial press having a moveable section, thesafety system including

a laser device for emitting a plurality of parallel continuous planarbeams having a generally constant lateral width;

a light receiver for receiving the planar beams and for detecting whenan object intersects at least one of the planar beams; and

a controller for stopping or preventing motion of the moveable sectionwhen the receiving means detects that at least one of the planar beamshas intersected an object,

said controller further adapted to decelerate the moveable section froma first speed to a second speed within a deceleration zone said zonedefined between a first point at which a first planar beam passes aspeed control point and a second point at which a second planar beampasses the speed control point.

The laser device and the light receiver may be similar in constructionto those described in the above noted International patent application.The laser device according to the present invention may however emit aplurality of said continuous planar laser beams, the laser beams beingposition at least generally parallel relative to each other. The use ofa single laser device to emit the laser beams facilitates correctalignment of the laser beams relative to each other. To this end, thelaser device may include a plurality of laser emitters for respectivelyemitting a laser beam, and a lens assembly for respectively convertingeach said laser beam emitted from a said laser emitter to a saidcontinuous planar laser beam. The lens assembly may include acylindrical prism for initially expanding the or each laser beam into aplanar fan shaped laser beam, and a converging lens for refocussing thefan shaped laser beam to a planar laser beam having a generally constantlateral width. The same lens assembly may be used to convert each laserbeam to facilitate the correct alignment of the final planar laserbeams. It is however also envisaged that a series of laser devices beused to provide the continuous planar laser beams. The use of planarlaser beams provides a greater area of protection for the operator thelaser beams preferably extending laterally beyond opposing sides of themoveable section. The laser beams when intersected by an object are alsovisible to the operator.

A single said light receiver may be used to receive the laser beams. Thelight receiver may include an array of light receiving elements, theelements being aligned along a common axis and located at an end of areceiver body of the light receiver. A cylindrical lens may be providedto focus the laser beam onto the light receiver array. This arrangementfacilitates detection of the laser beams even when the industrial pressis producing vibration within the safety system.

A single light receiver may be used to detect the plurality of planarlaser beams. These laser beams may be multiplexed such that each laserbeam is sequentially turned off and on so that the light receiver onlydetects one of said laser beams at any one time. It is however also tobe appreciated that separate light receivers may be utilised for eachsaid laser beam so that multiplexing is not necessary. Issues ofalignment can be greater if more than one laser device and/or lightreceiver are used. Alternatively, a single light receiver having aplurality of cylindrical lens, each focussing a separate laser beam ontothe light receiver array.

The industrial press may further include a stationary section, and thelaser beams may be located between the moveable and stationary sectionsof the industrial press. The moveable section may include a leadingedge, and each laser beam may be spaced at a different distance to theleading edge. Preferably, two said planar laser beams are emitted by thelaser emitting means, with a first said planar laser beam being spacedfurther from the leading edge than a second said planar laser beam.

Safety systems having two beams are known with one such system describedin German Patent DE 19717299 (Fiesller) the contents of which areincorporated herein by reference. In the Fiesiler system the two beamsare separated by a “safety distance”, being the distance in which thetool must stop before causing permanent injury. When the lower beam ofthe Fiesiler system is broken, the system shuts down the machine and sostopping the tool. However, the top beam is not a safety beam. Unlikethe second beam described in the previous embodiment, the upper beam ofthe Fieslier system is used to measure the distance between the tool andthe lower beam, that is the “safety distance”. In calibrating the systemthe assembly for the safety system is raised until the upper beam isinterrupted by the tool automatically setting the safety distance and socalibrating the tool. It follows therefore that the upper beam isdistinct from a safety beam and, in fact, acts as a “limit switch” inorder to calibrate the machine. During operation of the machine theupper beam remains inactive to the normal operation of the machine.

The safety system may define a speed control point close to thestationary section. When the moveable section initially approaches thestationary section, the moveable section may be initially moving at arelatively high speed. When the first planar laser beam reaches thespeed control point, the moveable section may begin decelerating. Thatfirst planar beam is muted as it reaches the speed control point. Whenthe first planar beam is muted, whilst it has not been shut off, it doesnot act as a safety beam at this point. Instead it remains active forseveral reasons, possibly as a speed/distance/position measurementdevice. The system may be placed into a “test mode” by pressing a testbutton, on and depressing a foot switch (initiating a down or approachsignal the tool is descended towards the bottom tool (anvil). The bottomtool has placed on it the work piece that is going to be bent (allsubsequent bends are carried out on smaller thickness work pieces). Asthe top tool (with the laser at fixed distance from the leading edge ofthe tool) descends, and the laser obstructs a surface of work piece,this stops the tool. The test button is again pressed, and this confirmsthis point. The system has now recorded the position of the top surfaceof the work piece. From this position the system then calculates aposition a few mm's before this to establish the muting and crawl speedposition. This position needs to be as low as possible but still havesome tolerance for buckles or distortion in the work pieces. Once thisposition is “confirmed” as above the operator may continuously gothrough the bending process without interruption, as long as the workpieces remain at approximately the same thickness. If this thickness ischanged then the test and confirmation may simply be retested.

The system may have further facility to aid in the maximum efficiency ofa wife variety of press brakes. On a preferred embodiment dip switchesin the control system, only accessible to the installer, that candistance the crawl point from the muting point. Some press brakes canchange from high speed to slower speed very quickly, however many maytake a longer time /distance to change. Therefore the setting of Dipswitches can shift the crawl position above the mute position, forinstance, in 2 mm increments up to say a total of 8 mm. This ensuresthat when the system carries out the speed check points, the press maybe optimized to satisfy safety criteria and industry standards. Byadjusting the rate the machine changes speed in the press itself(deceleration) against the crawl speed position a specific speedcriteria, for instance, 50% of maximum or 25 mm/s may be achieved.

In a preferred embodiment when the first laser beam reaches the speedcontrol point the speed of the tool is instantaneously checked to haveslowed by approximately 20%. The crawl speed signal may be given justprior to this point (and can be adjusted further up with dip switches ifnecessary). Up until this first laser is “muted the stop safe distancefault indication is 13 mm (just less than the 14 mm be 4 am to tooltip). After the tool is slowing and only the second beam remains activethis stop distance fault indication is changed to 8.5 mm.

As the tool progresses, the speed control point crosses the mid pointbetween the two planar laser beams. At this point, a furtherinstantaneous speed check is done to ensure the tool has decelerated to50% of the maximum operating system and further that the maximumcalculated stopping distance has now reduced to a second distance. In afurther embodiment this mid point maximum stopping distance may be 8.5mm.

As the second planar laser beam reaches the speed control point, afurther instantaneous speed check is performed to ensure the tool istraveling at the final crawl speed, possibly 25 mm per second. In a morepreferred embodiment, the final crawl speed may be 20 mm per second butnot exceeding a threshold limit of 25 mm per second. At the final crawlspeed, the maximum stopping distance must not exceed a final maximumstopping distance, which in one embodiment may be 4 mm, which isconsidered to contact the hand of an operator and perhaps pinch, but notcause permanent injury, to the hand.

As will be clear to a person skilled in the art, the instantaneous speedmeasurement may be the measurement of speed over a small finite distanceand may be measured through the counting of pulses for a known pulserate of the planar laser beams. In a further preferred embodiment, onexceeding any of the maximum speed limits or maximum stopping distances,the machine may be automatically shut down and consequently theinstantaneous speed measurement may be a measure of compliance with saidlimits.

In a further preferred embodiment the permitted bend speed and so thespeed at which the tool contacts and forms the material may be 20 mm persecond. Alternatively, the permitted bend speed may be 10 mm per secondwhereupon the speed of the tool is further decelerated from the speed atwhich the second laser crosses the speed control speed deceleratingfurther to 10 mm per second at which point the tool crosses the speedcontrol point.

In one example arrangement, the first planar laser beam can be spacedabout 14 mm from the leading edge of the moveable section, and thesecond laser beam can be spaced about 4 mm from the leading edge.

Because the first laser beam can be spaced further from the leading edgethan the earlier safety system (typically 9.0 mm), a greater stoppingdistance can be provided. The speed of the moveable section canprogressively decrease when the first laser beam reaches the speedcontrol point so that the speed of the moveable section is not suddenlyslowed. The speed of the moveable section may be typically about 40 to50% of the initial high speed by the time the point between the firstand second planar laser beam reaches the speed control point. When thesecond planar laser beam finally reaches the speed control point, thespacing between the moveable and the stationary section is preferably 6mm or less and the moveable section may be moving at about 25 mm/s. Whenthe moveable section is moving at this speed, it can still stop in lessthan 4 mm if the second planar laser beam is interrupted. The moveablesection can at this point continue to move at the constant speed of 25mm/s. Alternatively, the moveable section can continue to deceleratefrom 25 mm/s to 10 mm/s and then continue to move at this final speed.There is no need to further slow the moveable section because IndustryStandards do not require the moveable section to be slowed when thespacing is 6 mm or less, this space being considered too narrow to allowany object to be trapped therebetween.

According to a second aspect of the present invention, there is provideda safety system for an industrial press having a moveable section, thesafety system including a laser device for emitting a continuous beam ofrectilinear cross-section having a generally constant lateral width andgenerally constant depth;

said rectilinear beam having a proximate and distal face relative to aleading edge of the moveable section;

a light receiver for receiving the rectilinear beam and for detectingwhen an object intersects at least a portion of the beam; and

a controller for stopping or preventing motion of the moveable sectionwhen the receiving means detects that at least a portion of therectilinear beam has intersected an object,

said controller further adapted to decelerate the moveable section froma first speed to a second speed within a deceleration zone said zonedefined between a first point at which the proximate face passes a speedcontrol point and a second point at which the distal face passes thespeed control point.

In the first aspect of the present invention the plurality of parallelcontinuous planar beams define an area having an upper and lower bounddetermined by the upper most and lower most beams. The width of the zoneis defined by the lateral width of the plurality of beams which incombination with the upper and lower bounds defines in a preferredembodiment a rectilinear zone. In a more preferred embodiment the firstaspect of the invention may have only two beams and so these two beamsmay define the upper and lower bounds. In the second aspect of thepresent invention this zone is defined by a single beam having bothheight and width dimensions and so defining the same zone as in thefirst aspect. However the single beam may provide further facility fordetecting obstructions between the upper and lower bounds.

In a preferred embodiment of the first aspect of the invention as a beampasses the speed control point the relevant beam is switched off so asto prevent stopping of the tool as the relevant beam is obstructed bythe work piece. For the second aspect of the present invention theanalogous function of the rectilinear beam as it crosses the speedcontrol point results in a progressive muting of the rectilinear beamsuch that the portion above the beam remains active and the portionbelow the beam remains in a muted form. In a more preferred embodimentthe portion of the rectilinear beam below the speed control point maystill function so as to pulse and therefore make speed measurementpossible.

In a further preferred embodiment the rectilinear beam may be sized soas to extend beyond the upper bound associated with an upper beam of thefirst aspect of the invention. This extension of the rectilinear beammay terminate so as to intersect with the tip of the tool such that thetip of the tool obstructs a small portion of the rectilinear beam. Thus,positioning of the rectilinear beam relative to the tip of the tool maybe located by adjustment of the single rectilinear beam. So as to ensurethat this partial obstruction by the tool tip does not trigger stoppageof the tool receivers associated with the obstructions may be inactivewhilst maintaining the remaining receivers in an active condition.

According to a third aspect of the present invention, there is provideda method of operating a safety system for an industrial press having amoveable section and a stationary section, the safety system providing aplurality of continuous planar laser beams having a generally constantlateral width, each laser beam being spaced at varying distances fromthe moveable section, the method including moving the moveable sectiontowards the stationary section at a relatively high speed;

starting deceleration of the moveable section when one said laser beamreaches a speed control point located immediately adjacent thestationary section, moving the moveable section at a final crawl speedwhen a second said laser beam reaches the speed control point, themoveable section continuing to move at said final crawl speed towardssaid stationary section.

The moveable section may progressively decelerate until the final crawlspeed is reached for the moveable section.

In a fourth aspect of the present invention there is provided a methodfor setting the safety distance between a single planar laser beam and aleading edge of a moveable section of an industrial press, the methodincluding the steps of :

-   converging the planar beam along an axis parallel to the movement of    the moveable section until the leading edge interrupts the planar    beam;-   diverging the planar beam away from the leading edge along the axis    by a pre-determined distance, said pre-determined distance set as    the safety distance.

Said method involves automatically raising a single planar beam untilthe leading edge of the tool intersects said beam. The control thenlowers the emitter and receivers for the planar laser beam at a fixeddistance established for the safety distance corresponding to theindustrial press. Thus, for commissioning a new safety system, thesafety system assembly may be mounted to the industrial press in anappropriate fashion and by manually, or preferably engaging an automaticcommissioning controller, the controller will guide the necessaryemitter and receiver relationship up to the leading edge of the tooluntil intersecting said beam. The automatic system, or manualadjustment, can then be similarly guided to a predetermined distancefrom the leading edge of the tool and thus establish the safetydistance.

Whilst mounting any safety system will be of a similar intensityrequiring labour and time, with systems of the past commissioning ofsaid safety system can be equally labour intensive. With the presentmethod, commissioning of the safety system is automated and thus isquick and straight forward.

It will be convenient to further describe the invention by reference tothe accompanying drawings which illustrate an example arrangement of thepresent invention. Other arrangements of the invention are possible, andconsequently the particularity of the accompanying drawings is not beunderstood to be superseding the generality of the preceding descriptionof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side schematic view of the laser device and light receiverof the safety system according to a first aspect of the presentinvention.

FIG. 2 is a plan schematic view of the laser device and light receiverof FIG. 1;

FIG. 3 is a detailed view of an industrial press tool showing theorientation of the planar laser beams according to a first aspect thepresent invention.

FIG. 4 is a side schematic view of the laser device and light receiverof the safety system according to a second aspect of the presentinvention.

FIG. 5 is a plan schematic view of the laser device and light receiverof FIG. 4.

FIG. 6 is a detailed view of an industrial press tool showing theorientation of the rectilinear laser beam according to a second aspectof the present invention.

FIG. 7 is a detailed view of the rectilinear beam of FIG. 6.

Referring initially to FIGS. 1 and 2, the safety system includes a laserdevice 1 and a light receiver 2. Both the laser device 1 and lightreceiver 2 are similar in construction to the arrangement shown in theApplicant's International Patent Application No. PCT/AU00/00420 and willnot therefore be described in detail herein. The primary difference isthat the laser device 1 includes a pair of laser emitters 3, eachemitter 3 emitting a single laser beam 6. The laser beam 6 passesthrough a lens assembly 5 to convert that laser beam into a continuousplanar laser beam 7 a, 7 b. The lens assembly 5 typically includes acylindrical prism 9 for initially expanding the laser beam 6 into aplanar fan shape beam. This beam is then passed through a converginglens 11 and focussing lens assembly 13 for converting the laser beaminto said planar laser beam 7 a, 7 b. A window 15 is provided in frontof the lens assembly, and the planar laser beam 7 a, 7 b passes throughthe window 15. This planar laser beam 7 a, 7 b can typically have awidth “a” of about 50 mm.

Both of the laser beams 6 emitted by laser emitters 3 pass through thelens assembly 5 such that two separate planar laser beams 7 a, 7 b areemitted from the laser device 1. The laser beams 7 a, 7 b extendparallel to each other and laterally forwardly and rearwardly relativeto the tool 25 as shown in FIG. 3.

The light receiver 2 includes a window 17 through which the laser beams7 a, 7 b can pass, a cylindrical lens 19 for focussing the laser beamsonto a light receiver array 21. These cylindrical lens 19 ensures thatthe laser beams 7 a, 7 b focussed on the light receiver array 21 evenwhen there is vibration of the safety system during operation of theindustrial press.

The laser beams may be multiplexed such that each laser emitter 3 isturned on and off sequentially so that only one laser beam 7 a, 7 b atany one time is received by the light receiver 2. The light receiver 2therefore only detects a single laser beam 7 a, 7 b at any one time.This ensures that any interception of one or both laser beams 7 a, 7 bcan be detected.

FIG. 3 shows in more detail the orientation of the planar laser beams 7a, 7 b relative to a tool 25 of the moveable section of the industrialpress. According to the present invention, the laser device 1 and lightreceiver 2 are both mounted and moveable together with the moveablesection of the industrial press. Therefore, the planar laser beam 7 a, 7b can be located at a preset spacing away from a peripheral edge 27 ofthe tool 25. In one example arrangement, the first planar laser beam 7 acan be located approximately 14 mm from the tool peripheral edge 27. Thesecond laser beam 7 b can be located about 4 mm from the tool peripheraledge 27. There is therefore a spacing b of 10 mm between the first laserbeam 7 a and second laser beam 7 b.

This arrangement facilitates the use of higher tool speeds for themoveable section of the industrial press. The moveable section can forexample move at a downward speed of about 200-250 mm/s (compared with150 mm/s of current press brakes). The location of the first laser beam7 a enables a longer stopping distance to be set in the system, forexample, 13 mm.

During operation of the industrial press, when the first laser beam 7 areaches a speed control point provided a short distance above astationary section of the industrial press, the moveable section beginsto decelerate and the first laser beam 7 a is shut off. Therefore, asthe tool 25 of the moveable section continues to move downwards, whenthe speed control point is positioned intermediate the first laser beam7 a and the second laser beam 7 b, the speed can be anywhere between 40to 50% of the initial tool speed.

When the first planar beam 7 a reaches the speed control point the tool25 is traveling at 100% of its operational speed. At this point aninstantaneous speed check is conducted so as to ensure the maximumstopping distance at this speed is maintained at 13 mm.

As the tool 25 progresses, the speed control point crosses the mid pointbetween the two planar laser beams 7 b. At this point, a furtherinstantaneous speed check is done to ensure the tool 25 has deceleratedto 50% of the maximum operating system and further that the maximumcalculated stopping distance has now reduced to 8.5 mm.

As the second planar laser beam 7 b reaches the speed control point, afurther instantaneous speed check is performed to ensure the tool 25 istraveling at the final crawl speed, possibly 25 mm per second. In a morepreferred embodiment, the final crawl speed may be 20 mm per second butnot exceeding a threshold limit of 25 mm per second. At the final crawlspeed, the maximum stopping distance must not exceed a final maximumstopping distance, of 4 mm, which is considered to contact the hand ofan operator and perhaps pinch, but not cause permanent injury, to thehand.

As will be clear to a person skilled in the art, the instantaneous speedmeasurement may be the measurement of speed over a small finite distanceand may be measured through the counting of pulses for a known pulserate of the planar laser beams. In a further preferred embodiment, onexceeding any of the maximum speed limits or maximum stopping distances,the machine may be automatically shut down and consequently theinstantaneous speed measurement may be a measure of compliance with saidlimits.

In a further preferred embodiment the permitted bend speed and so thespeed at which the tool 25 contacts and forms the material may be 20 mmper second. Alternatively, the permitted bend speed may be 10 mm persecond whereupon the speed of the tool 25 is further decelerated fromthe speed at which the second laser crosses the speed control speeddecelerating further to 10 mm per second at which point the tool 25crosses the speed control point.

The present invention allows for more precise control of the speed ofthe moveable section, with the blade being initially decelerated andthen moved at a final crawl speed. This helps to reduce the overallproduction cycle of the machine.

FIGS. 4 and 5 show a schematic view of the safety system according to asecond aspect of the present invention whereby a rectilinear beam 28having height dimension c and width d in the range of the action of thetool 25.

A laser 31 is passed through an arrangement of lenses 30 so as to createan expanded beam 28 of substantial height and width which issubsequently focused through a second arrangement of lenses 33 ontoreceivers 32.

FIG. 6 shows the effect of the rectilinear beam as compared to theplanar beam arrangement of the first aspect of the present invention.The planar beams 7 a and 7 b define upper and lower bounds of the safetyzone in the second aspect of the present invention this zone is “filledin” by the manipulation of a single beam. The effect of having anenhanced safety zone remains similar to that of the first aspect and thebenefits of having deceleration zone defined between the upper and lowerbounds is maintained also. The primary difference in this case isfirstly the safety zone is defined by a single emitter rather than dualemitters with the dual beam system and secondly the central activeportion of the safety zone between lower bound 7 a and upper bound 7 b.

In the preferred embodiment shown in FIGS. 6 and 7 a further adaptationof the system may be seen whereby the rectilinear beam 28 extendstowards the tool 25 beyond the upper bond 7 b recognized by the systemshown in FIGS. 1 and 2. FIG. 6 shows the rectilinear beam 28 extendingup to and fractionally beyond the tool tip 27 whereby the tool tipobstructs a small portion 29 of the rectilinear beam 28. This has theadvantage of adjustment of the system such that on commissioning thesafety system with a new press brake the position of the rectilinearbeam 28 may be adjusted upwards until the tool tip 27 obstructs aportion 29 of the rectilinear beam. On registering this obstruction thesystem is initalized ready for use. This has distinct advantages overother systems in so far as the setting of this position is achievedthrough a single beam without sacrificing the protection offered by anexpanded zone. In order to achieve this result the portion 29 of therectilinear beam 28 will correspond to specific receivers which areinactive for the purposes of stopping the travel of the tool 25. Thus inoperation the safety system remains having a portion 29 obstructed butwith the corresponding receivers inactive for the purposes of safety thesystem will function until the remaining portion of the rectilinear beamis obstructed.

Modifications and variations as would be deemed obvious to the personskilled in the art are included within the ambit of the presentinvention.

1. A safety system for an industrial press having a moveable section,the safety system including a laser device for emitting a plurality ofparallel continuous planar beams having a generally constant lateralwidth; a light receiver for receiving the planar beams and for detectingwhen an object intersects at least one of the planar beams; and acontroller for stopping or preventing motion of the moveable sectionwhen the light receiver detects that at least one of the planar beamshas intersected an object, said controller further adapted to deceleratethe moveable section from a first speed to a second speed within adeceleration zone, said zone defined between a first point at which afirst planar beam passes a speed control point and a second point atwhich a second planar beam passes the speed control point.
 2. The safetysystem according to claim 1 wherein the first and second planar beamsare adjacent.
 3. The safety system according to claim 1 wherein thelaser device includes a plurality of laser emitters for respectivelyemitting a laser beam and a lens assembly for respectively convertingeach said laser beam emitted from a said laser emitter to a saidcontinuous planar laser beam.
 4. The safety system according to claim 3wherein the lens assembly includes a cylindrical prism for initiallyexpanding the or each laser beam into a planar fan-shaped laser beam anda converging lens for refocusing the fan-shaped laser beam to a planarlaser beam having a generally constant lateral width.
 5. The safetysystem according to claim 4 wherein the lens assembly is used to converteach laser beam to facilitate the correct alignment of the final planarlaser beam.
 6. The safety system according to claim 1 further includinga plurality of laser devices used to provide the continuous planar laserbeams.
 7. The safety system according to claim 4 wherein peripheraledges of the plane defined by the planar laser beam extend laterallybeyond opposing sides of the moveable section.
 8. The safety systemaccording to any one of the preceding claims wherein a single said lightreceiver is used to receive the planar beams.
 9. The safety systemaccording to claim 1 wherein the light receiver includes an array oflight receiving elements, the elements being aligned along a common axisand located at an end of a receiver body of the light receiver.
 10. Thesafety system according to claim 9 wherein a cylindrical lens isprovided to focus the planar laser beams onto the light receiver array.11. The safety system according to claim 1 wherein the planar laserbeams are multiplexed such that each laser beam is sequentially turnedoff and on creating pulses so that the light receiver only detects oneof said laser beams at one time.
 12. The safety system according toclaim 11 wherein the pulses are created at a pre-determined pulse rate.13. The safety system according to claim 1 wherein the industrial pressfurther includes a stationary section such that the laser beams arelocated between the moveable and stationary sections of the industrialpress.
 14. The safety system according to claim 13 wherein the moveablesection includes a leading edge and each laser beam is spaced at adifferent distance to the leading edge.
 15. The safety system accordingto claim 14 wherein there are two said planar laser beams emitted by thelaser emitting means with a first said planar laser beam being spacedfurther from the leading edge than a second said planar laser beam, saidfirst and second planar laser beams defining a single deceleration zone.16. The safety system according to claim 15 wherein the first and secondspeed of the moveable section is measured at the respective first pointand the second points.
 17. The safety system according to claim 16wherein the speed measurement is performed by the controller measuringthe number of pulses at the pulse rate as the moveable section travels apredetermined distance.
 18. The safety system according to claim 17wherein the predetermined distance is bisected by the speed controlpoint.
 19. The safety system according to claim 18 wherein thepredetermined distance is 2 mm commencing 1 mm above the speed controlpoint and finishing 1 mm below the speed control point.
 20. The safetysystem according to claim 16 wherein the first speed is a maximumoperating speed of the industrial press.
 21. The safety system accordingto claim 20 wherein the second speed is a final crawl speed.
 22. Thesafety system according to claim 21 wherein the controller deceleratesthe moveable section at a rate such that the speed of the moveablesection as a mid point between the first point and second point passesthe speed control point is 50% of the operating speed of the industrialpress.
 23. The safety system according to claim 21 wherein if the speedmeasurement detects a speed exceeding the first speed at the firstpoint, the final crawl speed at the second point or 50% of the operatingspeed at the mid point, then the controller will stop the moveablesection by shutting off the industrial press.
 24. The safety systemaccording to claim 1 wherein as each planar beam passes the speedcontrol point the respective planar laser beam is muted wherebyintersection of the planar beam by the object will not prevent motion ofthe moveable section.
 25. The safety system according to claim 24wherein the muted planar laser beam is still pulsed and speedmeasurement is still possible.
 26. The safety system according to claim16 wherein the speed control point is located 2 mm above a surface ofmaterial operated on by the industrial press.
 27. The safety systemaccording to claim 16 wherein the first and second planar laser beamsare spaced along an axis parallel to the movement of the moveablesection by 10 mm.
 28. The safety system according to claim 16 whereinthe first planar laser beam and the moveable section are spaced along anaxis parallel to the movement of the moveable section by 4 mm.
 29. Thesafety system according to claim 21 wherein the final crawl speed is 20mm per second.
 30. The safety system according to claim 16 wherein thecontroller further decelerates the moveable section from the secondpoint to a third point, said third point located at which the leadingedge of the moveable section passes the speed control point.
 31. Thesafety system according to claim 30 wherein the moveable section isdecelerated from 20 mm per second to 10 mm per second between the secondpoint and the third point.
 32. A safety system for an industrial presshaving a moveable section, the safety system including a laser devicefor emitting a continuous beam of rectilinear cross-section having agenerally constant lateral width and generally constant depth; saidrectilinear beam having a proximate and distal face relative to aleading edge of the moveable section; a light receiver for receiving therectilinear beam and for detecting when an object intersects at least aportion of the beam; and a controller for stopping or preventing motionof the moveable section when the light receiver detects that at least aportion of the rectilinear beam has intersected an object, saidcontroller further adapted to decelerate the moveable section from afirst speed to a second speed within a deceleration zone. said zonedefined between a first point at which the proximate face passes a speedcontrol point and a second point at which the distal face passes thespeed control point.
 33. The safety system according to claim 32 whereinthe first and second speed of the moveable section is measured at therespective first point and the second points.
 34. The safety systemaccording to claim 32 wherein the speed measurement is performed by thecontroller measuring the number of pulses at the pulse rate as themoveable section travels a predetermined distance.
 35. The safety systemaccording to claim 34 wherein the predetermined distance is bisected bythe speed control point.
 36. The safety system according to claim 35wherein the predetermined distance is 2 mm commencing 1 mm above thespeed control point and finishing 1 mm below the speed control point.37. The safety system according to claim 32 wherein the first speed is amaximum operating speed of the industrial press.
 38. The safety systemaccording to claim 37 wherein the second speed is a final crawl speed.39. The safety system according to claim 38 wherein the controllerdecelerates the moveable section at a rate such that the speed of themoveable section as a mid point between the first point and second pointpasses the speed control point is 50% of the operating speed of theindustrial press.
 40. The safety system according to claim 39 wherein ifthe speed measurement detects a speed exceeding the first speed at thefirst point, the final crawl speed at the second point or 50% of theoperating speed at the mid point, then the controller will stop themoveable section by turning off the industrial press.
 41. The safetysystem according to claim 32 wherein as the rectilinear beamprogressively passes the speed control point the rectilinear beam iscorrespondingly progressively muted whereby intersection of therectilinear beam at a muted portion of the rectilinear beam by theobject will not prevent motion of the moveable section.
 42. The safetysystem according to claim 41 wherein the muted portion of therectilinear beam is still pulsed and speed measurement is stillpossible.
 43. The safety system according to claim 32 wherein the speedcontrol point is located 2 mm above a surface of material operated on bythe industrial press.
 44. The safety system according to claim 32wherein the depth of the rectilinear beam is 10 mm.
 45. The safetysystem according to claim 32 wherein the proximate face and the moveablesection are spaced along an axis parallel to the movement of themoveable section by 4 mm.
 46. The safety system according to claim 40wherein the final crawl speed is 20 mm per second.
 47. The safety systemaccording to claim 46 wherein the controller further decelerates themoveable section from the second point to a third point, said thirdpoint located at which the leading edge of the moveable section passesthe speed control point.
 48. The safety system according to claim 47wherein the moveable section is decelerated from 20 mm per second to 10mm per second between the second point and the third point.
 49. Thesafety system according to claim 32 wherein the laser device includes aplurality of laser emitters for respectively emitting a laser beam and alens assembly for respectively converting each said laser beam emittedfrom a said laser emitter to a said continuous rectilinear laser beam.50. The safety system according to claim 49 wherein the lens assemblyincludes a first cylindrical prism for initially expanding the or eachlaser beam into a planar fan-shaped laser beam in one plane, a firstconverging lens for refocusing the fan-shaped laser beam to a planarlaser beam having the generally constant lateral width, a secondcylindrical prism, orthogonal to the first cylindrical prism, forexpanding the planar laser beam into a prismatic fan-shaped laser beamand a second converging lens for refocusing the prismatic fan-shapedlaser beam to a rectilinear laser beam having both the generallyconstant lateral width and the generally constant depth.
 51. The safetysystem according to claim 32 wherein the light receiver includes a twodimensional array of light receiving elements, the elements being placedin a rectilinear distribution and located at an end of a receiver bodyof the light receiver.
 52. The safety system according to claim 32 saidrectilinear beam further including a rectilinear portion of depthsufficient to span from the proximate face to a partial intersectionwith the leading edge of the moveable section, said rectilinear portionhaving the generally constant lateral width, wherein the light receiverfurther includes light receiving elements corresponding to therectilinear portion, such that the light receiving elementscorresponding to an area where the moveable section intersects with therectilinear portion do not function to prevent movement of the moveablesection.
 53. A method for setting the safety distance between a singleplanar laser beam and a leading edge of a moveable section of anindustrial press, the method including the steps of: converging theplanar beam along an axis parallel to the movement of the moveablesection until the leading edge interrupts the planar beam; diverging theplanar beam away from the leading edge along the axis by apre-determined distance, said pre-determined distance set as the safetydistance.
 54. The method according to claim 53 wherein the method isperformed under automatic control control.
 55. The method according toclaim 54 further including the step of actuating the automatic controlby an operator to calibrate the industrial press, said step precedingthe converging step.
 56. The method according to claim 53 wherein theplanar laser beam, associated emitters and receivers to generate anddetect the beam and the controller form part of a safety system mountedto the industrial press.
 57. A method of operating a safety system foran industrial press having a moveable section and a stationary section,the safety system providing a plurality of continuous planar laser beamshaving a generally constant lateral width, each laser beam being spacedat varying distances from the moveable section, the method includingmoving the moveable section towards the stationary section at arelatively high speed; starting deceleration of the moveable sectionwhen one said laser beam reaches a speed control point locatedimmediately adjacent the stationary section, moving the moveable sectionat a final crawl speed when a second said laser beam reaches the speedcontrol point, the moveable section continuing to move at said finalcrawl speed towards said stationary section.